From 1949, he was one of the regular sports car drivers with his Veritas RS. Despite usually being among the front-runners, he stood a little in the shadow of the top drivers like Ulmen and Rieß. Some good results were also spoiled by mechanical failures.

An early career highlight was a victory in the sports car race at Hockenheim in 1950, which was followed by a number of class wins in East Germany (Dessau 1959, Leipzig 1951, Rostock 1952). Like Rieß, he was invited into the Mercedes sports car team in 1952 to partner Helmut Niedermayr taking second place at Le Mans behind Rieß and Lang’s winning Mercedes. Two months later, at the Großer Preis von Deutschland sports car race, he beat the international competition by completing a Mercedes 1-2-3-4, finishing fourth behind compatriots Lang, Kling and Reiß. The same day, he drove his Veritas sports car in the Grand Prix; however, he only made it around one lap before retiring.

In 1953, at the end of a curious season, Theo found himself German Formula 2 champion without having won a single race! However, the rules were that in races open for ‘international’ drivers, points would be distributed among the best-placed West Germans only, thereby excluding East Germans like Edgar Barth who would have otherwise taken decisive points from Helfrich´s score. So, Helfrich’s results – 7th place at the Eifelrennen, 3rd place on the Avus, 12th place in the German Grand Prix and finally a 9th place at the Schauinsland hilclimb – were good enough for 14 points in the championship, one point ahead of the new rising star Hans Herrmann.

In August 1953 his season was crowned by a class victory and third overall in the 1.5-litre class of the Nürburging 1000 km race, driving for the Borgward factory team together with Adolf Brudes and Karl Günther Bechem. The 2-litre sports car class was no longer carried out in German events and so once again, Helfrich entered his ‘pontoon’ Veritas into the Grand Prix, this time making it to the finish two laps down on winner, Farina.

Finally, in 1954, when Formula 2 had been abandoned in Germany, Helfrich switched to Formula 3 racing in a Cooper, interrupted by a single Formula 1 start at the German Grand Prix in a rather hopeless effort with Hans Klenk’s old Veritas Meteor. He continued to race a Porsche 550 at occasional international events and hill climbs until 1957.